1. Field of the Disclosure
An exemplary embodiment relates to a display device, and more particularly, to an organic light emitting device.
2. Description of the Related Art
Among flat panel display devices, an organic light emitting device is a self-emission display device that does not require a backlight and has such characteristics that it can be formed to be light and thin, its process can be simplified, and it can be fabricated at a low temperature, has a high response speed of 1 ms or lower, a low power consumption, a wide viewing angle, and high contrast, etc.
The organic light emitting device may be classified into a top emission type device and a bottom emission type device depending on an emission direction of light, and also may be classified into a passive matrix type device and an active matrix type device depending on a driving method.
The active matrix type device is operated such that when a scan signal and a data signal are supplied to a plurality of subpixels arranged in a matrix format on a display unit, transistors, capacitors, and organic light emitting diodes (OLEDs) positioned in each subpixel are driven to display an image.
The OLED device receives the data and scan signals from devices positioned at an outer side of a panel. Here, the image data received from the outside is stored in a host memory, undergoes a picture quality tuning process, is arranged by the frame, and is then supplied to the display unit.
In order to supply data signals by the frame, the data stored in the host memory is fetched (called or retrieved) by the bit through time division controlling. At this time, data to be currently supplied and data to be supplied next are discriminated, and in order to continuously read and write them, two or more display memories are generally and necessarily used.
The reason for using the two or more display memories is because, while reading data from the memory by supplying corresponding data to the display unit, new data cannot be written in the display memory unit, in terms of the arrangement structure of the subfields.
Thus, the driving method that necessarily uses the two or more display memories causes a loss of costs.
In order to avoid a problem of degradation of elements such as the TFT, the capacitor or the OLED, etc., monitor pixels are provided on a substrate at an outer side of the display unit, and power supplied to the subpixels positioned within the display unit is sampled and controlled according to the sampled value to thus compensate changed characteristics of the subpixels.
In this case, for a sample hold unit that samples the power supplied to the monitor pixels, it is important to consider driving conditions between interworking elements such as a writing or reading process of a display memory unit or a light emitting period or a non-emitting period of the subpixels.
Thus, in order to properly compensate the changed characteristics of the subpixels by using the monitor pixels and the sample hold unit, a method that may increase the efficiency and accuracy of sampling in consideration of the above-mentioned conditions is required.